(a) Field of the Invention
The present invention relates to a mechanism for automatically opening a reagent pack used in a test by a luminescence measurement system and a method of controlling an open needle in the mechanism.
(b) Description of the Related Art
Asepsis and specific biological cleanliness of work environment are required in various clinical sites, food factories, medicinal product manufacturing factories, sites of fundamental researches, and the like. In such the environment requiring the biological cleanliness, the number of microorganisms in the air (airborne bacteria), falling bacteria, adhesive bacteria, and the like are counted (viable bacteria count). As a method of measuring airborne bacteria, an airborne bacteria sampler for collecting floating bacteria by natural fall of floating bacteria and by suctioning a certain amount of air has been commonly employed.
In these methods, ordinarily, floating bacteria are collected on an agar plate, cultured by a thermostat device for two to three days, and a number of colonies generated after the culture is counted as the number of viable bacteria. However, this method has a problem that it requires long time to culture viable bacteria.
Meanwhile, as a method capable of counting the number of microorganisms in short time, a method of converting the number of microorganisms by measuring ATP (Adenosine TriPhosphate) being an intracellular component by a bioluminescence method is well known.
The bioluminescence method employs a luciferin-luciferase luminescence reaction, where a luminescence reagent which contains basic luciferin and enzyme luciferase is mixed with a sample solution which contains ATP extracted from a cell of microorganism, ATP amount is obtained from a luminescence amount which is produced by the reaction, and the number of viable bacteria is calculated based on ATP amount per one viable bacterium. Patent document 1 discloses a kit for counting the number of viable bacteria by using such the luminescence reaction.
According to a method of counting the number of viable bacteria by a kit disclosed in Japanese Unexamined Patent Application Publication No. H11-155597 (Patent document 1), it is possible to achieve the assured effect in terms of reduction of measurement time. However, in a case where ultra minute amount of viable bacteria is subjected to count, a luminescence amount itself is minute. Therefore, there is a problem of great influence of background luminescence caused by such as inclusion of residual ATP and ATP not to be counted, and it is impossible to obtain good measurement accuracy.
Meanwhile, in a luminescence measurement system disclosed in Japanese Unexamined Patent Application Publication No. 2008-249628 (Patent document 2), viable bacteria adhered to a nozzle for dispensing a reagent and background luminescence derived from residual ATP are controlled, so that luminescence measurement can be conducted accurately and promptly.
According to the luminescence measurement system disclosed in the Patent document 2, it is considered possible to measure accurately and promptly even though minute amount of viable bacteria is luminescence-counted. However, in a case where viable bacteria count in minute amount is possible by the system disclosed in Patent document 2, contamination inside the system exerts great influence on a count value. For example, a reagent used for luminescence measurement is set in the system after it is opened outside the system, there is a possibility of contamination occurred during a period from opening to setting in the system.